Problem: Add. $64.9 + 23 =$
Explanation: There are many ways to solve this problem. Let's see two ways we can solve it. Place value table Let's line up the numbers by their decimal places. Tens Ones $.$ Tenths $6$ ${4}$ $.$ ${9}$ $2$ $3$ $.$ ${0}$ Because ${23}$ is a whole number, we can add a decimal point and a $0$ behind to make the columns align. Now, let's add each place value column. Tens Ones $.$ Tenths $6$ ${4}$ $.$ ${9}$ $+$ $2$ ${3}$ $.$ ${0}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $8$ $7$ $.$ $9$ Decomposing the numbers We can group the whole numbers together and the decimals together. $\begin{aligned} &({64} + {23}) + {0.9}\\\\ &=87 + {0.9}\\\\ &=87.9 \end{aligned}$ $64.9 + 23=87.9$